1. Technical Field
The present invention relates to a cleaning liquid supplying apparatus that supplies cleaning liquid to a nozzle surface of a liquid droplet ejecting head mainly when the nozzle surface is wiped, and also relates to a liquid droplet ejecting apparatus including the cleaning liquid supplying apparatus.
2. Related Art
As this type of cleaning liquid supplying apparatus, there is known a cleaning liquid supplying apparatus incorporated in a maintenance unit for a print head that ejects UV ink by using an ink jet process, the cleaning liquid supplying apparatus including a cleaning liquid supplying pipe and a cleaning liquid supply switching unit (see JP-A-2014-168912).
A plurality of maintenance units are provided so as to correspond to a plurality of print heads. Each maintenance unit includes a moving body including a wiper that wipes a nozzle forming surface of the print head, caps that cap the nozzle forming surface, and a support member that supports the wiper and the caps, and a wiper driving mechanism that moves the moving body in a wiping direction. Further, each maintenance unit includes a head driving mechanism that moves the print head between a cleaning position and a receding position, and a cleaning liquid supplying pipe and a cleaning liquid supply switching unit that supply cleaning liquid to the print head.
The cleaning liquid supplying pipe is arranged at the side of the print head which has moved to the cleaning position. The cleaning liquid supplying pipe has a plurality of ejecting ports arrayed in an extending direction. At the time of wiping with the wiper, the cleaning liquid supply switching unit is operated so as to eject the cleaning liquid from the plurality of ejecting ports toward the side surface of the print head.
It is assumed that the cleaning liquid supplying system including the cleaning liquid supplying pipe and the cleaning liquid supply switching unit also includes a cleaning liquid tank that stores the cleaning liquid, and a cleaning liquid pump that sends the cleaning liquid in the cleaning liquid tank to the cleaning liquid supplying pipe. In this case, a plurality of cleaning liquid supplying pipes are provided so as to correspond to the plurality of print heads. Therefore, it is assumed that the cleaning liquid tube that connects the cleaning liquid tank, the cleaning liquid pump, and the plurality of cleaning liquid supplying pipes to one another is constituted by a main tube that extends from the cleaning liquid tank via the cleaning liquid pump, and a plurality of branch tubes that branch from the main tube on the upstream side of the plurality of cleaning liquid supplying pipes. Further, it is assumed that opening/closing valves are provided in the plurality of branch tubes, respectively, thereby constituting the cleaning liquid supply switching unit.
In the cleaning liquid supplying system that supplies the cleaning liquid from the single cleaning liquid pump to the plurality of cleaning liquid supplying pipes as in the above-mentioned assumptions, there is a problem that the amount of cleaning liquid to be ejected from each cleaning liquid supplying pipe may vary depending on the number of opening/closing valves that are opened simultaneously. Specifically, in this cleaning liquid supplying system, the ejection amount of the cleaning liquid pump equals the total sum of the amounts of cleaning liquid supplied to the plurality of cleaning liquid supplying pipes, and hence the amount of cleaning liquid supplied to each cleaning liquid supplying pipe increases as the number of opening/closing valves opened decreases, whereas the amount of cleaning liquid supplied to each cleaning liquid supplying pipe decreases as the number of opening/closing valves opened increases. Therefore, there is a problem that the ejection flow rate and the ejection pressure of each cleaning liquid supplying pipe may become unstable. As a matter of course, the problem may be solved when a plurality of cleaning liquid pumps are provided so as to correspond to the plurality of cleaning liquid supplying pipes. However, the provision of a plurality of cleaning liquid pumps may raise the need for an installation space corresponding to the plurality of cleaning liquid pumps, and may cause an increase in cost.